Selective Hydrogenation Of α,β-unsaturated Aldehydes Or Ketones And Alkynes Catalyzed By Thermoregulated Phase-Separable Ruthenium Nanoparticles

Ru nanoparticles stabilized by ionic liquids ILPEG1000([CH3(OCH2CH2)nN+Et3][CH3SO3], n=22) were prepared through hydrogen reduction of RuCl3·3H2O. The thermoregulated phase-separable system consisted of ILPEG1000-stabilized Ru nanoparticles and n-heptane、 toluene possesses the thermoregulated phase-transition property, that is to say, at room temperature before reaction, the lower ILPEG1000phase containing Ru nanoparticles and the upper organic phase containing substrate and solvent are immiscible. When the temperature gradually elevates to the reaction temperature, the biphasic system mingle to a single phase and the reaction proceeds in it smoothly. When the temperature decreases to room temperature, the system becomes biphasic again. The product can be separated from the catalyst easily through simple phase separation and the catalyst can be reused again.ILpEG1000-stabilized Ru nanoparticles were used as catalyst in the selective hydrogenation of α,β-unsaturated aldehydes or ketones, the catalyst exhibited highly catalytic activity and selectivity. For the selective hydrogenation of cinnamaldehyde, under the optimal reaction conditions:T=120℃, t=7h, PH2=4MPa, cinnamaldehyde/Ru=250(molar ratio), the conversion of cinnamaldehyde was100%and the selectivity to hydrocinnamaldehyde was more than99%. The catalyst could be reused for4times without evident loss in activity and selectivity. The turnover number (TON) was1,223.ILpEG1000-stabilized Ru nanoparticles were used as catalyst in the selective hydrogenation of alkynes, the catalyst also exhibited good catalytic effect, for the selective hydrogenation of phenylacetylene, under the optimal reaction conditions:T=105℃, t=2h, PH2=1MPa, phenylacetylene/Ru=500(molar ratio), the conversion of phenylacetylene was95%and the selectivity to styrene was94%. The catalyst could be reused for4times without evident loss in activity and selectivity. The turnover number (TON) was2,195.